#!/usr/bin/env python3
"""Generated Mininet topology.  Do not edit by hand."""

import shlex

from mininet.cli import CLI
from mininet.link import TCLink
from mininet.net import Mininet


def _shell_join(args):
    """Quote command arguments for execution inside a Mininet node."""

    return ' '.join(shlex.quote(str(arg)) for arg in args)


def _node_cmd(node, *args):
    """Execute one safely quoted command inside a Mininet node."""

    return node.cmd(_shell_join(args))


def _start_background(node, args, log_path):
    """Start one background process and return its shell PID."""

    command = _shell_join(args)
    shell_command = (
        command
        + ' >'
        + shlex.quote(log_path)
        + ' 2>&1 & echo $!'
    )
    return node.cmd('sh -c ' + shlex.quote(shell_command)).strip()


def main():
    """Build, configure, expose, and clean up the planned network."""

    net = Mininet(controller=None, build=False)
    nodes = {}
    service_processes = []

    try:
        # Create nodes.
        nodes['h1'] = net.addHost('h1', ip=None)
        nodes['h2'] = net.addHost('h2', ip=None)
        nodes['h3'] = net.addHost('h3', ip=None)
        nodes['s1'] = net.addSwitch('s1', failMode='standalone')
        nodes['s2'] = net.addSwitch('s2', failMode='standalone')
        nodes['r0'] = net.addHost('r0', ip=None)

        # Create links.
        net.addLink(
            nodes['h1'],
            nodes['s1'],
            intfName1='h1-eth0',
            intfName2='s1-eth0',
        )
        net.addLink(
            nodes['h2'],
            nodes['s1'],
            intfName1='h2-eth0',
            intfName2='s1-eth1',
        )
        net.addLink(
            nodes['h3'],
            nodes['s2'],
            intfName1='h3-eth0',
            intfName2='s2-eth0',
        )
        net.addLink(
            nodes['r0'],
            nodes['s1'],
            intfName1='r0-eth0',
            intfName2='s1-eth2',
        )
        net.addLink(
            nodes['r0'],
            nodes['s2'],
            intfName1='r0-eth1',
            intfName2='s2-eth1',
        )

        # Materialize the Mininet topology.
        net.build()
        net.start()

        # Configure concrete interfaces.
        _node_cmd(nodes['h1'], 'ip', '-4', 'addr', 'flush', 'dev', 'h1-eth0')
        _node_cmd(nodes['h1'], 'ip', 'link', 'set', 'dev', 'h1-eth0', 'up')
        _node_cmd(nodes['h2'], 'ip', '-4', 'addr', 'flush', 'dev', 'h2-eth0')
        _node_cmd(nodes['h2'], 'ip', 'link', 'set', 'dev', 'h2-eth0', 'up')
        _node_cmd(nodes['h3'], 'ip', '-4', 'addr', 'flush', 'dev', 'h3-eth0')
        _node_cmd(nodes['h3'], 'ip', 'addr', 'add', '192.168.2.10/24', 'dev', 'h3-eth0')
        _node_cmd(nodes['h3'], 'ip', 'link', 'set', 'dev', 'h3-eth0', 'up')
        _node_cmd(nodes['r0'], 'ip', '-4', 'addr', 'flush', 'dev', 'r0-eth0')
        _node_cmd(nodes['r0'], 'ip', 'addr', 'add', '192.168.1.1/24', 'dev', 'r0-eth0')
        _node_cmd(nodes['r0'], 'ip', 'link', 'set', 'dev', 'r0-eth0', 'up')
        _node_cmd(nodes['r0'], 'ip', '-4', 'addr', 'flush', 'dev', 'r0-eth1')
        _node_cmd(nodes['r0'], 'ip', 'addr', 'add', '192.168.2.1/24', 'dev', 'r0-eth1')
        _node_cmd(nodes['r0'], 'ip', 'link', 'set', 'dev', 'r0-eth1', 'up')

        # Configure static default routes.
        _node_cmd(nodes['h3'], 'ip', 'route', 'replace', 'default', 'via', '192.168.2.1', 'dev', 'h3-eth0')

        # Apply node-level networking settings.
        _node_cmd(nodes['r0'], 'sysctl', '-w', 'net.ipv4.ip_forward=1')
        _node_cmd(nodes['r0'], 'sysctl', '-w', 'net.ipv4.conf.all.rp_filter=0')
        _node_cmd(nodes['r0'], 'sysctl', '-w', 'net.ipv4.conf.default.rp_filter=0')
        _node_cmd(nodes['r0'], 'sysctl', '-w', 'net.ipv4.conf.r0-eth0.rp_filter=0')
        _node_cmd(nodes['r0'], 'sysctl', '-w', 'net.ipv4.conf.r0-eth1.rp_filter=0')

        # Start planned services.
        _node_cmd(nodes['r0'], 'rm', '-f', '/tmp/mininet-dnsmasq-0.leases', '/tmp/mininet-dnsmasq-0.pid')
        pid = _start_background(
            nodes['r0'],
            ['dnsmasq', '--no-daemon', '--conf-file=', '--port=0', '--bind-interfaces', '--dhcp-authoritative', '--interface=r0-eth0', '--dhcp-range=192.168.1.100,192.168.1.200,12h', '--dhcp-leasefile=/tmp/mininet-dnsmasq-0.leases', '--pid-file=/tmp/mininet-dnsmasq-0.pid', '--dhcp-option=3,192.168.1.1'],
            '/tmp/mininet-dnsmasq-0.log',
        )
        service_processes.append((nodes['r0'], pid))

        # DHCP clients are intentionally not started here.
        # The assignment captures DHCP before dhclient is run manually.
        CLI(net)

    finally:
        # Stop only the service processes started by this script.
        for node, pid in reversed(service_processes):
            if pid:
                _node_cmd(node, 'kill', pid)

        net.stop()


if __name__ == '__main__':
    main()